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Galaxy Dx-959 No Am Modulation/power/transmit

8113 Northern MN

Active Member
Aug 9, 2013
156
19
28
43
Virginia,MN
Alright, well yesterday I undertook a mission to install some extra channels in this here DX959. All went well with the Double SPST switches and the P5 and P6 wires. Everything was fine and started to put it back together.

Buddy was sitting here and ya know how two guys get when they start talking "more power". We started going through the radio making sure everything was tuned up to spec. Surprisingly we found out that even brand new untouched from the factory the radio was set below the factory settings. Specifically the Bias and Voltages were extremely low. 40,42,43 and 44 were all tuned low. So spent a few hours getting the radio tuned to service manual specs. Exactly 12 Watts on SSB and 4 Dead key. AND then, it all went downhill. My DX949 set a bit above factory specs is putting out some pretty gnarly numbers and wanted to try to get this one to see what we could get the pep to show. Right around 22 watts pep on USB 20 I first started noticing a bit of heat from the chassis. Couple minutes later a bad smell and then NOTHING!

So the next few hours I spent with magnifying glass in hand searching through the board looking for what cooked. I found L48 in the bottom right corner...a 470uh Inductor. I promptly replaced it and fired up the radio. USB and LSB were back transmitting and showing Modulation on the stock meter and Correct Wattage on the Yaesu YS-60 Watt Meter. However, nothing is working on AM. I have searched through the board and unable to find anything else that visually looks fried. Im not sure where to start taking measurements to test out the AM transmit. Would like to spend today getting this working so if anyone could point me where to start taking voltages and measurements to test the AM I would greatly appreciate it!
 
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check the AM regulator mounted on the side of the case for voltages. it is the 3 legged unit with another smaller trans just to the side of it. you should have 13 volts on the 2 outer legs and about 5 volts on the center leg on transmit.. the old units had a 2sb754 in them and galaxy upgraded to a 2sb827. a 2sb817 is an even better unit if it is bad. here is a voltage chart for the 69610z boards so you can check them out. this will work for a dual final and a single final like the one you have.
 

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This Dx959 is actually using a EPT069611A board. It is stock with Dual 520s in the Final and Driver Position. The Voltage regulator is a 2sb827-0 and registering:

AM No Transmit:

Looking at the regulator with it standing in front of you Left Pin: 12.9 Center: 12.9 Right 13.5

AM Transmit:

Left: 12.7 Center: 12.7 and Right. 13.45
 
you have something going on there. the center leg voltage is too high. unsolder the center leg and see what you get on the center leg. if you have one change it out.
 
that trans is blown. be sure you did not drop solder any where. a chance you could have touched some thing while you were tuning the radio. there is a chance you could have blown Q55 right in front of Q54 also. just a heads up on the parts.
 
Yea no chance at all of dropped solder. Again it was working for quite awhile after the modification and only went haywire after trying to up voltages with Vr17 and the Bias slightly with VR10 and VR12. Was transmitting and we noticed the power on the meter drop to zero...smelled it and found L48 cooked. I will check Q54 and Q55 as well. Are the voltages the same as reported for the 69610z board?
 
Q55 On AM Keying down for TX

B: 11.9
C: 11.6
E: 12.6


So both Q54 and Q55 have really high voltages going to them on Transmit ....what would be the cause of this? Is there something else somewhere that could be causing the voltages to be so high other then then VR being bad?
 
Q54 the one mounted to the side of the case should not have high voltage on it when the leg is lifted unless it is shorted. that is why I said change it out if you have one. do you have a trans tester to check it out.
 
Yes i did pull it and used trans tester to confirm it was shot just a moment ago. I do not have another one of these laying around unfortunately. Gonna have to order one but gonna go with the upgraded one suggested in the mods.
 

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